Rough Running, Crude in Racor

[BoaterAl]

I'am going along with the above as algae due to water contamination. As your bus is still running I would do a 100 mile trip and change all filters again. As your photos show algae caught in your filters they have done there best to catch the crud until they can do no more. Fuel starvation is then the next level.
Racor vac gauges are not recommended in most highway applications due to the fact to being exposed to flying objects. In the marine applications the enclosed engine rooms offer protection for the gauge and secure from vibration being mounted on a bulk head.
The algae additive is a must in your case and the directions will suggest a double dose first time around. It's expensive ($20.00 plus) but cheaper then a fuel polishing treatment for sure.